Aryeh Kaplan was born in the Bronx, New York City to Samuel and Fannie (Lackman) Kaplan of the SefardiRecanati family from Salonika, Greece. His mother, Fannie Kaplan, died on December 31, 1947, when he was 13, and his two younger sisters, Sandra and Barbara, were sent to a foster home. Kaplan was expelled from public school after acting out, leading him to grow up as a "street kid" in the Bronx.
Kaplan did not grow up religious and was known as "Len". His family only had a small connection to Jewish practice, but he was encouraged to say Kaddish for his mother. On his first day at the minyan, Henoch Rosenberg, a 14-year KlausenburgerChassid, realized that Len was out of place, as he was not wearing tefillin or opening a siddur, and befriended him. Henoch Rosenberg and his siblings taught Kaplan Hebrew, and within a few days, Kaplan was learning Chumash.
In 1971 Kaplan moved to Brooklyn, New York, where he lived until the end of his life. Kaplan didn't hold any rabbinic positions in Brooklyn, but had many other positions which involved writing and editing religious publications:
Chaplain at Hunter and Baruch colleges (New York), from 1971 to 1972,
Associate Editor of Intercom, and Orthodox Jewish Scientists, from 1972 to 1973,
Editor of Union of Orthodox Jewish Congregations of America's Jewish Life magazine from 1973 to 1974, and
Director of publishing at the NCSY from 1974 to 1975
He also served as the rabbinic consultant for the play "Yentl"
Kaplan's books on Judaism and meditation were written between 1976 and 1982.
Gravesite of Rabbi Aryeh Kaplan
Kaplan died at his home of a heart attack on January 28, 1983, at the age of 48. He was buried in the Mount of Olives Jewish Cemetery, in Jerusalem, off Aweiss street, in the part known as "Agudas Achim Anshei America", "Chelek Alef" (Portion 1). His monument says that he was successful at doing Kiruv.
The Aryeh Kaplan Academy day school in Louisville, Kentucky, is named in honor of Rabbi Aryeh Kaplan.
Kaplan produced works on topics as varied as prayer, Jewish marriage and meditation. His writing was remarkably unique in that it incorporated ideas from across the spectrum of Rabbinic literature, including Kabbalah and Hasidut, without ignoring science. His introductory and background material contain much scholarly and original research. In researching his books, Kaplan once remarked: "I use my physics background to analyze and systematize data, very much as a physicist would deal with physical reality." This ability enabled him to undertake large projects, producing close to 50 books. His works have been translated into Czech, French, Hungarian, Modern Hebrew, Portuguese, Russian, German and Spanish.
Kaplan's major influence was Rabbi Zvi Aryeh Rosenfeld (1922-1978), who single-handedly introduced the teachings of Rebbe Nachman of Breslov to American shores beginning in the 1950s, inspiring many students at Brooklyn yeshivas, especially Torah Vodaas. Working together, Kaplan and Rosenfeld translated and annotated Rabbi Nachman's Tikkun (based on the Tikkun HaKlali). At Rosenfeld's suggestion, Kaplan also produced the first-ever English translation of Sichot HaRan ("Rabbi Nachman's Wisdom"), which Rosenfeld edited. He also translated and annotated Until the Mashiach: The Life of Rabbi Nachman, a day-to-day account of Rebbe Nachman's life, for the newly established Breslov Research Institute founded by Rosenfeld's son-in-law, Chaim Kramer. Kaplan's later writings further explored Hasidut, Kabbalah and Jewish meditation. (Kaplan himself utilized the meditative form of Kabbalah on a daily basis.) Kaplan wrote three well-known books on Jewish meditation. These books seek to revive and reconstruct ancient Jewish practices and vocabulary relating to meditation. He also wrote and translated several works related to Hasidic Judaism in general, and to the teachings of Rabbi Nachman of Breslov in particular.
Kaplan was described by Rabbi Pinchas Stolper, his original sponsor, as never fearing to speak his mind. "He saw harmony between science and Judaism, where many others saw otherwise. He put forward creative and original ideas and hypotheses, all the time anchoring them in classical works of rabbinic literature." His works reflect his physicist training—concise, systematic, and detail-oriented. His works continue to attract a wide readership, and are studied by both novices and the newly religious, as well as by scholars, where his extensive footnotes provide a unique resource.
"The Handbook of Jewish Thought," produced early in his career, is an encyclopedic and systematic treatment of Judaism's fundamental beliefs in two volumes, the first of which was published in Kaplan's lifetime. Because of the work's structure and detail, the references, with the index, can serve as a research resource across almost all of rabbinic literature. A chapter titled "Creation," in which Rabbi Kaplan "presents evolution as part of the basic tenets of Judaism," was omitted from publication.
"Torah Anthology," a 45-volume translation of Me'am Lo'ez from Ladino (Judæo-Spanish) into English. Rabbi Kaplan was the primary translator.
"Tefillin: God, Man and Tefillin"; "Love Means Reaching Out"; "Maimonides' Principles"; "The Fundamentals of Jewish Faith"; "The Waters of Eden: The Mystery of the Mikvah"; "Jerusalem: Eye of the Universe" — a series of highly popular and influential booklets on aspects of Jewish philosophy which span the entire spectrum of Jewish thought, as well as various religious practices. Published by the Orthodox Union/NCSY or as an anthology by Artscroll, 1991, ISBN1-57819-468-7.
Five booklets of the Young Israel Intercollegiate Hashkafa Series — "Belief in God"; "Free Will and the Purpose of Creation"; "The Jew"; "Love and the Commandments"; and "The Structure of Jewish Law" launched his writing career. He was also a frequent contributor to The Jewish Observer. (These articles have been published as a collection: Artscroll, 1986, ISBN0-89906-173-7)
"If You Were God," his final work, was published posthumously in 1983. Moving beyond superficiality, the slender book encourages the reader to ponder topics concerning the nature of being and Divine providence.
^"Rav Mendel Weinbach"(PDF). p. 13. In 1952, Rabbi Simcha Wasserman .. to found a yeshivah in Los Angeles.. asked Rabbi Gedaliah Schorr .. Torah vodaath, to give him a small cadre of talmidim. .. Nisson Wolpin, Meier Weinberg, and Aryeh Kaplan
^Brill, Alan in Aryeh Kaplan on Evolution- A Missing Chapter of The Handbook of Jewish Thought (October 2019). In this chapter, annotated by an editor to be of questionable propriety, Rabbi Kaplan argues that "there is overwhelming evidence from astronomy, geology, radioactive dating, and fossils, that this initial creation took place billions of years ago" (first page, 15:5 [see source for citation's endnotes, omitted from above quotation]). He acknowledges that there are those who would reject the scientific evidence, but asserts that it's an "inconceivable" argument that God would mislead mankind in presenting a creation older than its true age (ibid.).
^The second volume, posthumously published, references Kaplan's "1967-1969 manuscript that consisted of 40 chapters," 13 of which were "published in 1979 as the Handbook of Jewish Thought;" and that of the remaining chapters (which were clearly "set aside with the thought of eventually preparing them for publication"), only 25 are printed in Volume 2. This "indicates that 2 chapters of the original 40 were suppressed" (Brill, Alan in Aryeh Kaplan on Evolution- A Missing Chapter of The Handbook of Jewish Thought).